Someone just mentioned needing this website for this year, so here you go. One thing to remember, is that if you are flying in or out of an airport that is located where a school holiday begins or ends, you will pay a higher price. I have saved a lot of money by taking a train to another city to fly out of, because they were not on vacation and Hessen was. Use this tool to get better airfares. It will really make a difference.
http://www.holidays-info.com/School-Holidays-Germany/2010/school-holidays_2010.html